:root {
  --container-padding: 2rem;
  --card-gap: 1.5rem;
  --primary-color: #3b82f6;
  --secondary-color: #f3f4f6;
  --border-color: #e5e7eb;
}

.exercise-container {
  padding: var(--container-padding);
}

.page-title {
  font-size: 1.5rem;
  font-weight: bold;
  color: #1a1a1a;
  margin-bottom: 1.5rem;
}

.loading, .error {
  padding: 1rem;
  font-size: 1rem;
}

.error { color: #dc3545; }
.loading { color: #6b7280; }

/* 统一卡片样式 */
.exercise-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: var(--card-gap);
  margin-bottom: 2rem;
}

.exercise-card {
  border: 1px solid var(--border-color);
  border-radius: 8px;
  background-color: white;
  transition: transform 0.2s, box-shadow 0.2s;
  min-width: 250px;
}

.exercise-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

.card-body { padding: 1.25rem; }

.card-title {
  font-size: 1.125rem;
  color: #111827;
  margin-bottom: 0.75rem;
}

.card-text {
  color: #6b7280;
  line-height: 1.5;
  margin-bottom: 1.5rem;
}

.status-badge {
  display: inline-block;
  padding: 0.25rem 0.5rem;
  border-radius: 100px;
  font-size: 0.75rem;
  font-weight: 500;
}

/* 统一按钮样式 */
.btn {
  padding: 0.4rem 0.8rem;
  border-radius: 4px;
  font-size: 0.875rem;
  transition: background-color 0.2s;
}

.btn-primary {
  background-color: var(--primary-color);
  border-color: var(--primary-color);
  color: white;
}

.btn-primary:hover { background-color: #2563eb; }

.btn-secondary {
  background-color: var(--secondary-color);
  color: #374151;
  border: 1px solid var(--border-color);
}

.btn-secondary:hover { background-color: #e5e7eb; }

/* 无数据提示 */
.no-data提示 {
  padding: 8rem 2rem;
  text-align: center;
  color: #6b7280;
}

/* 响应式调整 */
@media (min-width: 768px) {
  .exercise-grid {
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: calc(var(--card-gap) * 1.5);
  }
}

@media (min-width: 1024px) {
  .exercise-container { padding: calc(var(--container-padding) * 2); }
}
